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By Yilin Fang, Alain Bonneville, Timothy. D. Scheibe, Zhijie Xu

"We present a hydro-mechanical model for geological sequestration of carbon dioxide. The model considers the poroelastic effects by taking into account the coupling between the geomechanical response and the fluid flow in greater detail. The simplified hydro-mechanical model includes the geomechanical part that relies on the linear elasticity, while the fluid flow is based on the Darcy's law. Two parts were coupled using the standard linear poroelasticity. Analytical solutions for pressure field were obtained for a typical geological sequestration scenario. The model predicts the temporal and spatial variation of pressure field and effects of permeability and elastic modulus of formation on the fluid pressure distribution.IntroductionIn order to achieve a substantial reduction of CO2 emissions and alleviate the atmospheric carbon problem, massive scale carbon sequestration is required involving millions of tons of carbon dioxide injection over several decades. The geomechanical response is important upon the injection of substantial supercritical carbon dioxide into deep geological formations. Supercritical CO2 is less dense than brine waters and the buoyancy driven flow of CO2 requires the aquifer to be capped by low permeability rock (""caprock"") to prevent the upward migration of C02 (as shown in Fig.1 ). Massive scale injection of C02 changes the overall stress state in the caprock and formation. This change leads to large deformation that can damage the caprock, create fractures, and open new flow paths for supercritical C02. Therefore, a coupled hydromechanical model becomes essential for the caprock integrity analysis."

Jan 1, 2012

By Qiang Zhong, Bin Xu, Qian Li, Wei Gao, Yongbin Yang, Yaxuan Wang

Lump coal with high volatility is used for providing heat and reductive gas, and ensuring permeability in COREX. However, it is apt to be pulverized in transport and storage process. Therefore, comprehensive utilization of the pulverized coal to produce coal briquettes with appropriate binders is significant, among which the molasses binder cannot meet the technological requirements. In this paper, coal tar pitch binder and BJ additive were used in briquetting and carbonizing process of coal powder. The results showed that BJ effectively activated cold state cohesiveness of the pitch and make it bond the coke particles to a firm briquette at room temperature .Carbonizations of coal and coal tar pitch achieved obvious constriction and formed a carbonized skeleton. The drop resistance of wet briquettes reached over 50 times/1meter. When cured at 1000 °C for 1h under nitrogen atmosphere, the compressive strength of carbonized briquettes came to 6.43 Mpa.

Jan 1, 2016

By R. A. Spitz, R. Leiby, M. Bricker

Electrochemistry plays a significant role in minimizing wastes at East Penn's secondary lead smelter. East Penn has been recovering spent battery acid for reuse in new batteries since 1992. East Penn also produces a fertilizer feedstock from sulfur dioxide in the smelter stack gases. The success of these processes is, in large part, due to the installation of electrochemical cells. The cells in the acid recovery plant allow the waste from this process to be concentrated into less that 10% of the original spent acid. The cells in the fertilizer plant treat the solution to remove dissolved metals prior to sale to fertilizer manufacturers.

Jan 1, 2000

By F. Baldini, M. S. Borges

"The proposed method emphasizes the optimization of waste management with regard to the exploitation of raw materials incorporated in the remains of industry, as well as the economics of natural resources as an environmental impact assessment. This system [tool] allows: (a) the conversion of an environmental liability into an asset by finding a line of appropriate research for each type of waste and the development of new materials applicable to other industries, (b) the performance of internal control of the waste generated (production, storage, final destination) as well as legal conformity.Objectives:1.1 General objective:To design a collaborative system for socio-environmental management of industrial waste.1.2 Specific objective:Develop evidence of concepts;Evaluate the deployment of the inventory of waste in an industry;Enable the conversion of an environmental liability into an asset by finding a line of research appropriate to the waste: a case study;Evaluate the environmental legislation in the legal mechanisms that influence company decisions.IntroductionThe global economy is undergoing major changes, among these changes; it should be highlighted those related to technological progress and environmental quality.While the industrialized countries and higher levels of economic growth dominate modem technology, developing countries are identified by a different growth pattern, using the annual growth rate of Gross Domestic Product per capita [3, 18].Growth is when the GDP grows, in percent, over the previous year. Development, on the other hand, is when the countries change their technologies and improve their internal structure. Thus, the growth considers the accumulation of wealth, while the development is concerned with the distribution of wealth, improvement of the quality oflife and environmental quality [3, 18].As the UNESCO report shows (1999), the biggest problem is between consumption and development, what is produced and the end that is given to the product. Therefore, product and by-product have equal importance in the quantity produced [29].On one hand there is a positive relationship between indicators of economic growth and technological progress, however, on the other hand, these transformations are a paradox, confirmed by the dramatic use of environmental resources and the lack of technologies for recycling of industrial scrap."

Jan 1, 2011

By Torma A. E.

Biotechnological processes are considered to be cost effective especially for situations where the recovery of metals from 'Very large volumes containing trace metal concentrations (less than 10 ppm) is concerned. Microorganisms, alive or dead, or their products can be highly efficient and selective biosorbents for metal concentration. It is important that the metal bound to the biosorbent can be stripped by suitable agent(s) and regenerated for repeated use. The stripped solution should be concentrated enough to be introduced into the common metal recovery circuit. The industrial acceptance of biosorption processes is dictated by increased competitive advantage over other processes. This paper reviews the pertinent literature?, regroups the information, and points out future possibilities for the mineral and metal processing industries.

Jan 1, 1992

By Michal Stepien, Piotr Palimaka, Stanislaw Pietrzyk

During the steel scrap melting process in an electric arc furnaces, the generated dust may contain a significant amount of zinc. The content of zinc in case of melting galvanized steel scrap is variable and ranges from 15 to 40 wt%. This dust cannot be re-used for the steelmaking process. On the other hand the zinc content is too low to treat the steel dust as a feedstock in pyrometallurgy of zinc. When they are disposed in land fills they have adversely effect the environment. This work presents selected results of research and development of new technology, which was developed in order to utilization steelmaking dust in the sintering process. One of the products (zinc-rich) can be used as a high-quality raw material for production of zinc by pyro- or hydrometallurgical processes. The second one product from the shaft furnace can be used as a feedstock for the steelmaking process.

Mar 1, 2017

By Jonkion M. Font

Due to the known disadvantages of the use of iron silicate slag in the nickel converting stage, i.e., high metal losses, high magnetite content, and low fixation of impurities in the slag, the development of the new proposed "ferrous calcium silicate slag" for smelting and converting processes of nickel is very promising. Hence, considering the successful experimental results of using CaO base slag for the nickel smelting process, a study based on a detailed comparison for the phase equilibrium, and the minor elements distribution between the Ni3S2-FeS matte with either FeOx-CaO or FeOX-Si02 base slag was investigated. The main results are summarized as: no difference in the nickel losses between both slags was found at high nickel content in the matte, and the fractional distribution analysis for arsenic and antimony pointed out their preferential fixation in the calcium ferrite slag rather than in the iron silicate slag. Considering the energy and pollution issues, the technical feasibility of using calcium ferrite slag in a converting process of the Bessemer matte will have a prominent future for the nickel industry.

Jan 1, 2003

By Bowen Li, Canhua Li, Mingsheng He

Steelmaking slag is a by-product in considerable volume and a valuable material for various applications. In general, steelmaking slag is an alkaline compound of CaO, Fe2O3, and SiO2. However, its characteristics varies depending on the feedstocks, steelmaking process and cooling method of the slag. To utilize this by-product effectively, this study investigated the characteristics of steelmaking slags taken from Wuhan Iron & Steel Co. Ltd. The results showed that the slags mainly consist of the oxides of calcium, iron, and silicon, with low contents of magnesia, alumina, and manganese oxide with a feature of high alkalinity and lime saturation factor. The major mineral phases include belite, calcium ferrite, calcium hydroxide, wustite, quartz, and small amount of elite. Thermogravimetric analysis indicated the weight loss from ambient temperature to 800 °C is 8% in total. Melting test showed the glass transition temperature is between 1300 and 1350 °C, flow temperature is about 1400 °C. The slag samples investigated in this study can be considered as a typical glass-ceramic composite.

Mar 1, 2018

By Gaifeng Xue, Lijun Lu, Honghui Fang, Jiannyang Hwang

"Steel slag has been stockpiled in many steel mills due to its poor performance in various construction related applications. Free lime in steel slag has been considered as a major barrier for its utilizations. Composite of steel slag and powders of granulated blast furnace slag have been found an excellent cementitious material for concrete. Portland cement is not required in this kind of concrete. Concretes with various amounts of steel slag and powders of granulated blast furnace slag additions have been investigated. Physical and chemical properties of the products were examined. High performance concrete can be obtained. Field testing of the concrete products was conducted for various applications, including buildings and pavements, and the results demonstrated the soundness of the concrete. Drill cores of field tested concrete, with ages up to 26 years, were examined for the microstructures under SEM.IntroductionIn the steel industry, a major source of the solid waste is steel slag. Steel slag has poor stability in construction applications. This is a major reason that only a small amount of steel slag has been utilized. Some of the reported applications include the land filling/creation in the sea, road base materials, soil treatment for acid neutralization and micronutrients supply, and sintering aid in the sintering plant of the steel industry [1].To solve the stability problem for using steel slag as construction materials, the common approach is to find a method capable of depressing or eliminating the expansion of steel slag. Free lime in steel slag is the major component that causes the expansion. Aging and hydration pretreatment of free lime in steel slag are the well known methods for increasing the steel slag stability. However, there has been limited success on these approaches due to that a large portion of free lime is locked in the grains during the pretreatment process."

Jan 1, 2012

By N. J. Themelis

The basic chemical, thermal and transport principles that underlie sulfide smelting of. copper, nickel and lead are reviewed. Two basic types of modern smelting processes are distinguished?: flash-smelting, where the predominant reactions occur between oxygen-bearing gas and concentrate particles dispersed therein; and bath-smelting where the concentrate is enveloped and reacted in a turbulent bath of matte, slag and gas. The controlling heat and mass transfer phenomena are discussed, and appropriate correlations are proposed.

Jan 1, 1983

By Li Qian

Mechanisms of bio-dephosphorization from iron ore was investigated in this Paper. The results show that there are two bio-dephosphorization ways from iron ore, the one is that Acidithiobacillus ferrooxidans directly derive phosphorus from the ore, the other is phosphorus is able to be leached acid produced during metabolizing of Acidithiobacillus ferrooxidans, and the latter is more important than the other. Adding suitable pyrite can enhance the bio- dephosphorization process through providing nourishment and producing acid directly due to S 3oxidized or indirectly due to Fe3 as oxidant. The potential varies in the range of 0.434~0.498V and pH is in the range of 2.5 ~ 1.25 during bio-leaching process. It can be founded that, according 2+to the E-pH graph of Fe-H2O system, Fe wouldn?t be oxidized under sterile system in this potential and pH ranges. It can be obviously concluded that the Acidithiobacillus ferrooxidans are 2+able to reduce the potential for the oxidization of Fe and make the oxidization occur in the above pH and potential zone, so the bio-leaching process can proceed. the investigation of E-pH graph of P-H2O system show that H3PO4 can exist steadily.

Jan 1, 2009

By Pengfu Tan

A thermo-chemical model of the copper P-S converter and a viscosity model for the converter slag have been developed to predict the behavior of magnetite in the converter slag, amounts of slag and matte, compositions of slag and matte, volume of the bath, bath temperature, slag blow endpoint determination, SEMTECH OPC signals, and the viscosity of converter slags. The predictions of bath temperature, slag and matte compositions, and magnetite content in the slag have been validated by the industrial data. The effects of fluxing strategy, returns and skim charges, oxygen enrichment, and temperature on the magnetite formation in the slag have been predicted and discussed. The effect of oxygen potential, SiO2/Fe in slag, detection of slag blow endpoint, and temperature on Fe3O4 content in converter slag, slag viscosity, liquidus temperature of converter slag and skimming operation has been modeled and discussed as well. Some applications of the industrial operations have been presented.

Jan 1, 2009

By Guan-zhou Qiu, Shui-shi Liu, Yu-feng Guo, Tao Jiang

"The preparation of high-quality synthetic ruitle from electric furnace titanium slag was systematically investigated by activation roasting followed by acid leaching process. The results showed that impurities such as Ca and Mg in titanium slag can be effectively removed and TiO2 grade of the product was markedly improved by the process. High-quality synthetic rutile containing 88.54% TiO2, 0.42% (CaO+MgO) was obtained under the conditions that roasted with 7.5%(wt) H3PO4 at 1000 oC for 2h, followed by two-stage leaching in boiling dilute sulfuric acid for 2h. Mechanism studies showed that anosovite solid solution and silicate minerals were reacted with phosphoric acid in the roasting process. As a result, titanium components in titanium slag turned into rutile (TiO2) and impurities were transformed into acid-soluble phosphate and quartz.IntroductionWith the gradual depletion of natural rutile and the rapid development of titanium industry in China, the natural rutile reserves cannot satisfy the requirement for production of titanium pigment and titanium sponge. Ilmenite is, therefore, becoming main raw material for titanium industry. However, because of its low TiO2 grade, it generally requires preconcentration to titanium-rich material such as titanium slag or synthetic rutile [1-3].Ilmenite resources are extremely rich in Pan-xi area of China, which account for 90.54% of total ilmenite reserves in China [4]. The titanium slag produced by electric smelting of ilmenite concentrate has high contents of Ca and Mg, and is not suitable as a raw material for chloride process and titanium sponge production. Therefore, upgrading titanium slag to prepare raw material suitable for chloride process and titanium sponge production has important significance for the development of China's titanium industry."

Jan 1, 2011

By Zhang Hanbo, Niu Liping, Zhang Zhiqi, He Jicheng, Dou Zhihe

"Rutile, ilmenite and Al-Ca complex reducer were used to prepare high titanium ferrous alloy by enhanced reduction-SHS method. The effects of the complex reducer compositions and slag types on the enhanced reduction-SHS process were investigated. The high titanium ferrous alloys were characterized by XRD and SEM. The results indicate that the high titanium ferrous alloys consist mainly of TiFe2, AlTi3 and Al2O3. The oxide inclusions exist resulting in directly the high oxygen content and micro-structural defects in the alloys. The titanium and oxygen contents decrease, but the aluminum content in the alloy increases while the mass ratio of calcium in the Al-Ca complex reducers increases. When the mass ratio of Al/Ca in the Al-Ca complex reducer is 6:1, titanium, oxygen and aluminum contents are 63.75%, 3.01% and 10.72% respectively. When the mass ratio of Al/Ca is 5:1 titanium content is 55.00% nearly and aluminum content is higher than 14.00%, but oxygen content is lower than 2.0%.1. IntroductionThe high titanium ferroalloys with 65%~75% titanium have the advantages of low melting point and high titanium content. They are widely used in special steel refining, while they are also a kind of very important quality orientation alloys in the rage of aviation and aerospace. At present, the methods of preparing high titanium ferroalloy include vacuum remelting and thermit reduction. The alloys prepared by the vacuum remelting method have good qualities and low oxygen content, so it is widely used in Russia, Western Europe and other developed countries. In China, there are abundant rutile resources, but waste titanium is lack, therefore, the preparation method is the thermit reduction. But there are many quality defects in the high ferrotitanium alloy, including high oxygen content, unstable quality and so on. In order to improve the qualities of the high titanium ferroalloy, especially to reduce oxygen content, the domestic and overseas have done a lot of further researches. For example, Sichuan E-mei ferroalloy plant and Beijing Nonferrous Metal Research Institute have prepared high titanium ferrous with 73.77% titanium with natural rutile, but the oxygen content is high. Through controlling the quality of raw material, they obtained the better qualities, but the oxygen content is still very high. South Africa Mintek company have prepared high titanium ferrous alloy with low nitrate by plasma heating under the isolation air conditions, but they couldn’t also remove effectively oxygen in the alloy. The oxygen exists in the form of Al2O3 and titanium protoxide. So it can be speculated that except TiO2 not being fully reduced, the no-sufficient alloy-slag separation is the direct reason resulting in high oxygen and poor microstructure. In view of present technical difficulties during preparing high titanium ferroalloy by thermit reduction, this paper proposed a new method of preparing high titanium ferrous with low oxygen by enhanced reduction-SHS with Al-Ca complex reducer. Ca in Al-Ca complex reducer has stronger reductive ability, it can effectively strengthen the reductive degree of TiO2. The slagging agent CaO CaF2 and MgO can effectively reduce the viscosity of Al2O3 slag to improve its liquidities to strengthen alloy-slag separation effects so that to remove inclusions and oxygen. In this paper, effects of slagging agent type on the reduction and the qualities of high-titanium ferroalloy were studied."

Jan 1, 2012

By Jürgen Antrekowitsch, Thomas Griessacher

"Heavy metal containing residues are typically hazardous wastes because on the one hand, a deposition gets more and more complicated and on the other hand, the large amounts of metals like Zn, Cu, Fe and Pb represent a significant value. Thus, a post-treatment of these materials with the recovery/recycling of the metals and stabilization of the waste is not only ecological but often also economical. The therefore typically applied recycling processes utilize pyrometallurgical steps, where carbon or carbon monoxide from fossil coal and coke is used as a reducing agent, which results in large amounts of CO2 emissions. An alternative option is the application of a hydrogen-rich gas emitted in biomass utilization processes as a carbon-neutral reducing agent. Investigations in a retort process which were done at different temperatures and times showed excellent results concerning the achievable reduction rates and final contents of the heavy metals for various residues.IntroductionNowadays heavy metal containing residues like electric arc furnace dust (EAFD), dust from cupola furnaces, waelz slag, etc. are declared as hazardous wastes in a growing number of countries due to the leachability of the heavy metals in these residues. For that reason it is no longer possible to landfill these materials or use them for road construction or disposal works. Some land filling activities, carried out until now, have only been realizable because of some process modifications or cost intensive post-treatment steps of these residues. But the disposal capacities for such materials are decreasing, therefore increasing the prices. The second point for the growing disposal limitations is the stringent environmental legislations and regulations, which restrict the number and amounts of materials which can be dumped [1 – 5].From the other point of view these heavy metal containing residues usually have high contents of zinc, lead, iron, etc., which represent a significant value and therefore a big potential to recover these metals. This is why in recent years the number of recycling processes and the amount of recycled heavy metal containing residues have continuously increased. These recycling processes have the target to recover the valuable metals from the residual materials in the form of a saleable product as well as the stabilization of the slag produced in these processes [5, 6]."

Jan 1, 2011

By T. V. Jayaraman, D. Das, B. Mallesham, A. R. James

The PNN-PZT xPb(Ni0.3Nb0.67)03-(1-x)Pb(Zr0.31 Ti0 69)03 (0.2=x=0.6) based relaxor-ferroelectric material was synthesized by colurnbite precursor (NiNb206) method via conventional solid state reaction. Homogeneous mixture of required oxides and precursor was calcined at 850°C for 4 hrs to obtain phase pure perovskite. Pellets of PNN-PZT ceramics were sintered at 1100oC for 4 hrs. Phase pure perovskite structure was confirmed by the X-ray diffraction analysis. From the X-ray diffraction analysis it is also confirmed that there is a structural transformation from the rhombohedral to tetragonal with increase in PZT content and existence of morphotrophic phase boundary (MPB) at x = 0.5 composition. The morphology and microstructure of the sintered pellets were observed using the scanning electron microscope. P-E loop measurement shows the high remnant polarization (19.12 µC/cm2) and low coercive field (6.89 kV/cm) at MPB compared to all other compositions. The electromechanical planar coupling coefficient (kp) was measured through the resonance and anti-resonance method using the LCR meter. The piezoelectric strain coefficient (d33) measured directly using the d33-meter. At x = 0.5 composition the highest value of d33 = 398 pC/N is obtained.

Jan 1, 2012

By Heikki Tuovinen

The total utilization of raw materials and energy is the most important criterion when planning. industrial processes. The main goal is clearly to use the raw materials and energy as effectively as possible in order to make the desired products directly in the primary process itself', or to recycle unused materials and energy either as such, or after cleaning back into the process. However, few industrial processes are so straightforward. Most processes generate by-streams of materials and energy, which cannot be recycled directly and it is namely these by-streams which tend to remain as wastes. These by-streams are slags, dusts, vaporized metals, liquids, slurries, sludges, gases etc. Most base metal processes produce all these by-products. Waste water and gas emission controls and regulations are tightening all the time, so new processes must be developed to keep pace with these requirements. These processes generate more solid wastes, which must be utilized or at least processed into a harmless form landfilling. Municipal and hazardous wastes also contain valuable materials and energy, which must be used to minimize landfilling. The development of processes for these purposes places even greater demands on research and development. The same principles and methods developed for mining, ore dressing and metal refining processes can also be adapted for research and development work on processes for waste minimization. However, the problems encountered are much more complicated and less familiar, demanding more versatile and accurate tools and equipment. This paper presents principles, examples and some references of R & D work on processes for waste minimization.

Jan 1, 1992

By Takahiro Miki

In order to use metallurgical grade silicon (MG-Si) as a starting material for solar cell, phosphorus has to be removed from silicon because phosphorus is a n-type dopant. On the other hand, silicon, ferrosilicon, and silicomanganese are widely used as deoxidizers in steel refining processes. Since most of the phosphorus introduced during the deoxidation process is brought into final products, it is important -to lower the phosphorus content of these alloys. Hence, thermodynamics of phosphorus in such metals is important for the evaluation of dephosphorization processes. In the present study, thermodynamic properties of phosphorus in molten Si-P alloys at 1723- 1848K and those of Si-Fe-P and Si-Mn-P alloys at 1723K have been determined by equilibrating respective metals in a controlled phosphorus partial pressure. The results are expressed as follows.

Jan 1, 1998

By I. U. Onyenanu, C. E. Ilochonwu, E. I. Nwonye, C. O. Nwajagu

This work shows how pure silica was derived directly from rice husks ash (RHA) in different temperatures for reduction to Silicon (Si). The processes to form Si materials are usually complex, costly and energy-intensive. The silica in the ash undergoes structural transformations depending on the conditions of combustion. A high purity silica was produced at 650oC after burning the rice husk (RH) for up to 7 hours. The purity of the silica was determined by dissolving the RHA with alkali solution to form sodium silicate solution of pH 11.0. This was added to hydrochloric acid of pH 1.5 which lowered the pH of the solution to 4.0 to form silica gels. The silica gels produced were washed and dried to powder and then characterized using XRD and EDX techniques. This study was done to reduce energy waste and environmental pollution in Nigeria as silica is used to develop many materials.

Jan 1, 2015

By S. Castro, P. Alfaro, C. Moctezuma

IMMSA operates a conventional roasting-leaching-purification-electrolysis plant for the production of zinc from concentrates in San Luis Potosi, Mexico. The leaching circuit was designed to take into consideration a feed mixture to the roaster with a maximum iron content of 7%. Since the start-up of the plant in 1982, the zinc recovery increased to 94.5%. However, an increase in the iron content in 1997 caused an important decrease in the global zinc recovery. Two new steps were added to the leaching circuit and modifications were made to the other steps in order to increase zinc extraction. Two new automated press filters were installed to replace the original vacuum drum filters and to minimize soluble zinc losses. Additionally, the residue treatment steps in purification were modified and a calcium removal circuit is just starting operation. These actions, besides improving the operations, have as the main objective to increase the global zinc recovery to levels above 94.5%.

Jan 1, 2000